Hiya Laura
With regards to DVD players MP3 speakers..think the best place to buy these would be Marmaris..the dolmus stops at the start of the Bazaa,and there are a few electrical shops before going into Bazaa./...not too sure on prices,some people may say differently but only place i can recall seing things like this,as they had all the PSP's and that in the window.
Dvd's and Cd's are easy,along the canal on the right hand side towards the beach...just near the end,a guys selling them all there..a friend of ours brought 10 Dvd's off him last week,was able to try them out first,but all of them working perfectly
Trainers..i'd say best place is the Bazaa in Marmaris,but would be able to get in
Icmeler depending on what you wanted
Hope this helps
Bec x